The atmosphere in the vacuum annealing furnace will directly affect the surface treatment effect of the product. The atmosphere in the furnace is determined by the airtightness of the vacuum furnace. Therefore, in order to ensure the quality of the workpiece, the airtightness of the vacuum furnace must be maintained firstly. The difficulty of the airtightness inspection of the vacuum annealing furnace lies in the large furnace area, complicated pipeline and easy leakage. There are many parts. The inspection of tightness must be regular and institutionalized. The following professional vacuum furnace manufacturer pin Jin for everyone to introduce in detail.
1. Determine the key parts of tightness inspection.
These key areas generally include:
1) replace parts of equipment during overhaul. The furnace and pipe parts that have been repaired during maintenance are the key parts of inspection.
2) open top cover, bottom cover, perforated hole and maintenance door.
3) inlet sealing roll gap.
4) Expansion joint on furnace shell and circulating pipe, furnace roller flange, heat exchanger flange, flange and weld of each instrument, etc.
5) water cooled pyrometer, camera, water cooled heat exchanger and so on.
6) analyzer sampling tube connector and so on.
2. Check the positive pressure part.
In the normal production process, the annealing furnace should maintain a 150-300Pa positive pressure.
1) the judgement of leakage. Observing the data measured by on-line oxygen ppm analyzer, when the residual oxygen of a certain section suddenly rises obviously, it may be the leakage of furnace shell or circulation pipeline.
2) leak detection methods and tools. Tool room hydrogen detector. The method is to ensure that the hydrogen content in the furnace is more than 3%. The gas tightness of the leaking furnace section is checked by the portable hydrogen detector. The key part is the overhaul weld. When the leak point is detected, the hydrogen detector will alarm.
3. Check the negative pressure part.
The suction end of the recirculating fan is negative pressure. If the negative pressure part leaks, the air will be inhaled into the furnace.
1) the judgement of leakage. By observing the change of the data measured by the online analyzer, it is possible to determine whether there is any leakage of the typhoon machine.
2) leak detection methods and tools. The negative pressure leak point can be checked by changing the negative pressure into positive pressure, and then by using a hydrogen detector, or by using a helium leak detector, a special device for negative pressure leak detection.
4. Leakage treatment
The annealing furnace is always in working condition. For some leakage points, high temperature sealant can be used to make temporary treatment, and the stoppage time should be given before thorough treatment.
Repair welding of cracked parts; replacing aging or damaged gaskets and rings; replacing parts with loopholes such as expansion joints; tightening loose bolts; applying high temperature sealant.
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